The aim of the present book will be to provide a comprehensive account of our present knowledge of the theory of dynamical phenomena exhibited by elose binary systems; and on the basis of such phenomena as have been attested by available observations to outline probable evolutionary trends of such systems in the course of time. The evolution of the stars - motivated by nuelear as weIl as gravitation al energy sources - constitutes nowadays a well-established branch of stellar astronomy. No theo ries of such an evolution are as yet sufficently specific - let alone infallible - not to require continual tests by a confrontation of their consequences with the observed prop erties of actual stars at different stages of their evolution. The discriminating power of such tests depends, of course, on the range of information offered by the test objects. Single stars which move alone in space are now known to represent only a minority of objects constituting our Galaxy (cf. Chapter 1-2); and are, moreover, not very revealing of their basic physical characteristics - such as their masses or absolute dimensions. If there were no binary systems in the sky, the only star whose vital statistics would be fully known to us would be our Sun.

Introduction to Close Binary Systems provides a comprehensive survey and guide to the fast-moving field of multiple, specifically binary, stars, with an up to date account of research around 'close', i.e. interacting pairs. Such interactions allow direct quantification of stellar properties, opening up factual insights into basic building blocks of the Universe. The book provides a much needed update for the seminal Close Binary Systems of Zdenĕk Kopal. Following a comparable plan, it presents relevant subject matter with an emphasis on building a framework of understanding to serve as a supporting resource for students and researchers. The text starts from a general historical background and progresses into the main theoretical ideas supporting our prima facie interpretation of observations. The central chapters explore further into these observational methods, arranged according to the classic subdivisions of astrometry, spectroscopy and photometry. Optimal inversion of observational data into model parametrization is a theme through these chapters. Significant here is the problem of how non-uniqueness in modelling affects interpretation. The underlying issues of stellar evolution bearing on observational evidence become paramount in the last four chapters. The book proceeds step-by-step from directly understandable examples of unevolved pairs to the challenging cases where stars are found in more and more extreme conditions, leading up to the mergers of massive black hole pairs seen in the new field of gravitational wave astronomy. This is a valuable reference for postgraduate and advanced undergraduate students working in mainstream areas of stellar astrophysics, with applications also to exoplanet research which shares some methodological features. Course designers for stellar astrophysics will find a useful selection of topics within this book. Key features: • Provides a well-explained and backgrounded, up-to-date account of close binary systems, in a fast-moving field of research that is growing in scientific importance • Surveys a wide range of case-studies within the context of binary and multiple star systems • Fills an acknowledged gap in current literature Cover Image: A public memorial to Zdenek Kopal in his home town (birthplace) of Litomysl in Czechia.

Astrophysical research has led to the detection of thousands of planets outside the Solar System. About one-tenth of the extrasolar planets discovered so far reside in binary- or multi-stellar systems, and some of the closest known rocky exoplanets populate these multiple-star systems. While such environments seem good places to look for a second Earth, can Earth-like planets with two or more suns be habitable? And do solar system-like configurations have to be detected to find a habitable exo-Earth?This book addresses these questions. Starting with a brief overview of the various types of double star-planet configurations that have been observed so far, the book discusses the intriguing variety of planetary motion in such environments, taking into account the stellar type, evolution, and activity, and elaborates on how the presence of an additional stellar companion affects planet formation, system architectures and the habitability of planets in binary star systems. New methodologies developed in this area of research are explained and demonstrated for systems such as Alpha-Centauri, HD41004, Kepler-35, and many others. This monograph provides a grand entry to the exciting results that we expect from new missions like TESS, CHEOPS and Plato.

Our conference - opening today - has two aims in view: first, to commemorate some milestones in the development of the studies of close binary systems whose anniversaries fall in these years, as well as to take stock of our present knowledge accumulated through out preceding decades, in order to consider where do we go from here. This summer, 310 years will have elapsed since the first ec lipsing binary - Algol - was discovered in Bologna by Geminiano Montanari (1633-1687) to be a variable star; and 198 years have gone by since John Goodricke of York (1764-1786) established the fact that Algol's light changes were periodic. Moreover, it is al most exactly (to a month) now 100 years since Edward Charles Pickering (1846-1919) of Harvard Observatory in the United States took the first steps towards the development of systematic methods of analysis of the light changes of Algol and related systems - a topic which will constitute the major part of the programme of our present conference. The three dates recalled above illustrate that the discoverers of such celestial objects and observers of their light changes have been systematically ahead of the theoreticians endea vouring to understand the significance of the observed data by de cades and centuries in the past - a fact which, incidentally, con tinues to hold good (albeit with a diminishing lead-time) up to the present.

This book contains the proceedings of the second joint research program on close binary systems between the People's Republic of China and the United States. The planning for the double stars conference developed gradually through several years of close cooperation between astronomers of the PRC and the US. Topics covered include interacting am binaries, H-alpha emission and polarization of RS CVn stars, observational approach to close binary evolution, the role of polarimetry in understanding close binary stars and their interactions, physical models for close binaries and logical constraints, and accretion disks in dwarf novae.

The proposal to organize a Symposium on circumstellar matter and extended atmo spheres in binary systems was first made by the Dominion Astrophysical Observatory to the Executive Committee of the International Astronomical Union in the summer of 1969. It received the support of the presidents of Commissions 29 (Stellar Spectra), 30 (Radial Velocities), 36 (Stellar Atmospheres), and 42 (Photometric Double Stars). Approval in principle was given by the Executive Committee almost immediately, and the Committee further suggested that the Symposium be officially designated the Struve Memorial Symposium. Final approval was given at the time of the 1970 General Assembly of the Union. when the dates of the Symposium were set for August or September, 1972. The Organizing Committee set up consisted of K. O. Wright (Chairman), A. H. Batten, K. -H. B6hm, A. A. Boyarchuk, G. Larsson-Leander, and M. Plavec. In addition, J. Sahade and F. B. Wood acted as advisory members. Local organization was entrusted to a committee consisting of A. H. Batten, E. K. Lee, and C. D. Scarfe. The final dates selected were September 6-12, 1972, and the Sym posium was held at the Island Hall Hotel, Parksville, B. C. , on Vancouver Island some 90 miles from Victoria. The Organizing Committee attempted to arrange a Symposium of the type in which no contributed papers would be presented and discussion would range as widely as possible over the field covered by the six invited review papers.

The zeta Aurigae stars are the rare but illustrious sub-group of binary stars that undergo the dramatic phenomenon of "chromospheric eclipse". This book provides detailed descriptions of the ten known systems, illustrates them richly with examples of new spectra, and places them in the context of stellar structure and evolution. Comprised of a large cool giant plus a small hot dwarf, these key eclipsing binaries reveal fascinating changes in their spectra very close to total eclipse, when the hot star shines through differing heights of the "chromosphere", or outer atmosphere, of the giant star. The phenomenon provides astrophysics with the means of analyzing the outer atmosphere of a giant star and how that material is shed into space. The physics of these critical events can be explained qualitatively, but it is more challenging to extract hard facts from the observations, and tough to model the chromosphere in any detail. The book offers current thinking on mechanisms for heating a star's chromosphere and on how a star loses mass, and relates this science synergistically to studies of other stars and binaries, and to the increasing relevance of contributions from new techniques in interferometry and asteroseismology. It also includes a detailed discussion of the enigmatic star epsilon Aurigae, which had recently undergone one of its very infrequent and very baffling eclipses. Though not a zeta Aurigae system, epsilon Aurigae is a true "Giant" among eclipsing stars. The 7 chapters of this book, written by a group of experts, have been carefully edited to form a coherent volume that offers a thorough overview of the subject to both professional and student.

In 1988, in an article on the analysis of the measurements of the variations in the radial velocities of a number of stars, Campbell, Walker, and Yang reported an - teresting phenomenon;the radial velocity variations of Cephei seemed to suggest the existence of a Jupiter-like planet around this star. This was a very exciting and, at the same time, very surprising discovery. It was exciting because if true, it would have marked the detection of the ?rst planet outside of our solar system. It was surprising because the planet-hosting star is the primary of a binary system with a separation less than 19 AU, a distance comparable to the planetary distances in our solar system. The moderatelyclose orbit of the stellar companionof Cephei raised questions about the reality of its planet. The skepticism over the interpretation of the results (which was primarily based on the idea that binary star systems with small sepa- tions would not be favorable places for planet formation) became so strong that in a subsequent paper in 1992, Walker and his colleagues suggested that the planet in the Cephei binary might not be real, and the variations in the radial velocity of this star might have been due to its chromospheric activities.